Dallas Mavericks rookie Cooper Flagg scored 45 points in a 134-128 win over the Los Angeles Lakers at American Airlines Center on Sunday, April 5.

Flagg became the first rookie to score 40 points in a game against LeBron James.

Flagg got off to a fast start, going 7-of-10 from the field for 19 points in the first quarter. He then finished the first half with 26 points.

James finished with a team-high 30 points as the Lakers continue to march toward the postseason without the services of Luka Doncic and Austin Reaves. While Doncic suffered a Grade 2 left hamstring strain that will sideline him for the rest of the regular season, Reaves suffered an oblique injury that is expected to keep him sidelined for four to six weeks.

In Sunday's game, Flagg and James made some history together. They are the first players in NBA history to score 20 or more points in the same game, with one player aged 40-plus and another a teenager, according to the NBA.

Coming off a career-high 51 points on April 3, Flagg is the first rookie since Allen Iverson during the 1996-97 season to score 40 or more points in back-to-back games, according to the NBA. Flagg has 40-plus point games this season and is averaging 20.8 points per game.

Here’s a breakdown of Flagg's performance against the Lakers on Sunday: